Polymides, process for producing the same and photosensitive composition the same

ABSTRACT

Polyimide is produced by reacting two kinds of diamine compounds consisting of diaminopolysiloxane and a carboxyl group-containing diamine or three kinds of diamine compounds consisting of diaminopolysiloxane, a carboxyl group-containing diamine and an aromatic or alicyclic diamine with a dicarboxylic acid anhydride having a 2,5-dioxotetrahydrofuryl group as one acid anhydride group, thereby once forming a polyamic acid, and subjecting the polyamic acid to polyimidization reaction. The resulting polyimide itself is soluble in low boiling organic solvents for general purpose use, typically methyl ethyl ketone. A photosensitive composition comprising the polyimide, a photo crosslinking agent and a photo acid-generating agent forms a negative type polyimide pattern upon development with an aqueous alkali solution.

This is a Continuation of application Ser. No. 09/259,069, filed Feb.26, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to polyimides, a process for producing thesame and a photosensitive composition containing the same, and moreparticularly to polyimides capable of giving a negative type polyimidepattern upon development with an aqueous alkaline solution, a processfor producing the same and a photosensitive composition containing thesame.

2. Description of Related Art

So far used photosensitive resins are typically polyester acrylate,epoxy acrylate, etc. To obtain a desired pattern upon exposure of thesephotosensitive resins to light, an organic solvent is used as adeveloping agent. Such organic solvent developing type, photosensitiveresins have such a serious problem as an adverse effect on theenvironments in addition to safety or sanitary problem during workingdue to the use of the organic solvent.

In place of the organic solvent developing type, photosensitive resinshaving such problems, alkali-developable photosensitive resins based onnovolak resins, polyvinylphenol etc. have been proposed and almost allof them have been utilized as positive type thin films having athickness of a several μm, but these positive type thin films have notalways satisfied the heat resistance, preservation stability, patternembedability, etc. required by FPC (flexible printed substrate)applications.

Furthermore, polyimide resins themselves are insoluble in an organicsolvent and therefore have so far relied on such a method of onceconverting them to organic solvent-soluble polyamic acids, followed bytheir polyimidization. However, some of polyimide resins themselves aresoluble in an organic solvent. For example, polyimide resins disclosedin JP-A-57-131227 and polyamide-imide resins disclosed in JP-A-59-145216are said to be soluble in an organic solvent and photosensitive.However, the organic solvent for that purpose is aprotic polar solventsincluding dimethylformamide, whereas acetone, benzene, cyclohexanol,etc., on the other hand, are used there for deposition of the resins.That is, the resins are insoluble in these latter organic solvents.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a polyimide by itselfsoluble in low boiling organic solvents for general purpose use,typically methyl ethyl ketone and capable of giving a negative typepattern upon development with an aqueous alkali solution, a process forproducing the same and a photosensitive composition containing the same.

According to the present invention, there is provided a novel polyimide,which is a copolymer comprising two kinds of diamine compoundsconsisting of diaminopolysiloxane and a carboxyl group-containingdiamine or three kinds of diamine compounds consisting ofdiaminopolysiloxane, a carboxyl group-containing diamine and an aromaticor alicyclic diamine, and a dicarboxylic acid anhydride having a2,5-dioxotetrahydrofuryl group as one acid anhydride group. Such apolyimide can be produced by reacting two kinds of diamine compoundsconsisting of diaminopolysiloxane and a carboxyl group-containingdiamine or three kinds of diamine compounds consisting ofdiaminopolysiloxane, a carboxyl group-containing diamine and an aromaticor alicyclic diamine with a dicarboxylic acid anhydride having a2,5-dioxotetrahydrofuryl group as one acid anhydride group, thereby onceforming polyamic acid, and then polyimidizing the polyamic acid. Theresulting polyimide can be formed into a photosensitive composition byadding a photo crosslinking agent and a photo acid-generating agentthereto.

DETAILED DESCRIPTION OF THE INVENTION

For diaminopolysiloxane, one component of two or three kinds of diaminecompounds, which react with the carboxylic acid anhydride, compoundsrepresented by the following general formula can be used:

where R is a divalent hydrocarbon group having 2 to 6 carbon atoms,preferably 3 to 5 carbon atoms; R₁ to R₄ are each a lower alkyl grouphaving 1 to 5 carbon atoms or a phenyl group; and n is an integer of 0to 30, preferably 4 to 12.

The compounds include, for example, compounds whose R and R₁ to R₄ arethe following substituents in combination:

R R1 R2 R3 R4 (CH₂)₃ CH₃ CH₃ CH₃ CH₃ (CH₂)₄ CH₃ CH₃ CH₃ CH₃ (CH₂)₃ CH₃C₆H₅ CH₃ C₆H₅ p-C₆H₄ CH₃ CH₃ CH₃ CH₃

Actually, the following commercially available products can be used:Toshiba Silicone products TSL9386, TSL9346 and TSL9306; TorayDow-Corning product BY16-853U, Shinetsu Chemical product X-22-161AS,Nippon Unicar product F2-053-01, etc.

The carboxyl group-containing diamine for use in the present inventionincludes, for example, 3,5-diaminobenzoic acid, 2,5-diaminoterephthalicacid, 2,2 ′-bis(aminobenzoic acid), etc. These carboxyl group-containingdiamines, when the produced polyimide is to be used as a photosensitiveresin, can be used so that the carboxyl group content is about 0.6 toabout 3.0% by mole, preferably about 0.7 to about 2.5% by mole in therepetition units [(a) and (b) or (a) to (c) which follow]. Below about0.5% by mole, the polyimide will be less soluble in an aqueous alkalisolution, whereas above about 3.0% by mole it will be too solubletherein.

The aromatic or alicyclic diamine for use in the present inventionincludes, for example, aromatic diamines such as3,3′-bis(aminophenyl)ether, 4,4′-bis(aminophenyl)ether,1,3-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone,bis[4-(3-aminophenoxy)phenyl]sulfone, 4,4′-diaminophenylsulfone,3,3′-diaminophenylsulfone, etc. or alicyclic diamines such as1,3-bis(aminomethyl)cyclohexane, 4,4′-bis(aminocyclohexyl)methane,3,3′-bis(aminocyclohexyl)methane, etc.

When two kinds of diamine compounds are used, diaminopolysiloxane isused in a proportion of about 20 to about 80% by mole, preferably about40 to about 70% by mole, whereas carboxyl group-containing diamine isused in a proportion of about 20 to about 80% by mole, preferably about30 to 60% by mole, where total is 100% by mole. When less than about 20%by mole of diaminopolysiloxane is used, no film can be formed, whereasabove about 80% by mole development by an aqueous alkali solution cannotbe made any more. When less than about 20% by mole of carboxylgroup-containing diamine is used, light-unexposed regions will beinsoluble in the aqueous alkali solution, whereas above about 80% bymole even light-exposed regions are soluble, but the difference indissolution rate between the light-exposed regions and thelight-unexposed regions will be smaller.

When three kinds of diamine compounds are used, diaminopolysiloxane isused in a proportion of about 20 to about 70% by mole, preferably about30% to about 50% by mole, carboxyl group-containing diamine in aproportion of about 20 to about 70% by mole, preferably about 30 toabout 50% by mole, and aromatic or alicyclic diamine in a proportion ofabout 10 to about 60% by mole, preferably about 20 to about 40% by mole,where total is 100% by mole. When the aromatic or alicyclic diamine isused in such a proportion, the polyimide resulting there from will havea higher light transmission in the ultraviolet zone, for example, asatisfactory photosensitivity even to a film as thick as 50 μm. When thearomatic or alicyclic diamine is used in a proportion of more than about60% by mole, polyimide will have a reduced solubility in the lowerboiling organic solvents for general purpose use.

Reaction between a mixture of diamine compounds and a dicarboxylic acidan hydride having a 2,5-dioxotetrahydrofuryl group as one acid anhydridegroup, for example,5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-carboxylic acidanhydride represented by the following formula:

is carried out preferably in an aprotic polar solvent such asdimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, etc., butcan be carried out even in a polar solvent such as cresol, pyridine,etc. Actually, the carboxylic acid anhydride is dropwise added to asolution of the mixture of diamino compounds in the polar solvent atabout 0° to about 10° C. and subjected to reaction at about 30° C. to150° C., preferably at about 50° to about 100° C., for about 2 to about8 hours. The dicarboxylic acid anhydride having a2,5-dioxotetrahydrofuryl group as one acid anhydride group for use inthe present invention further includes5-(2,5-dioxotetrahydrofuryl)-3-cyclohexene-1,2-carboxylic acidanhydride, 4-(2,5-dioxotetrahydrofuryl-3-yl)tetraline-1,2-carboxylicacid anhydride, etc.

The resulting reaction product is polyamic acid as a polyimideprecursor, and thus is subjected to dehydration reaction forpolyimidization. Dehydration reaction is carried out, after adjustmentof the concentration to about 10 to about 20% by weight with a polarorganic solvent, if necessary, at a temperature of about 150° to about250° C., preferably about 180° to about 200° C., for about 2 to about 6hour, preferably about 2 to about 4 hour, preferably by using adehydrating agent such as acetic anhydride, pyridine, etc., where it isalso effective to use toluene, etc. to subject the formed water toazeotropic distillation.

Siloxanepolyimide, which is a polyimidazation reaction product, can bepresumed to be a block copolymer having repetition units (a) and (b)represented by the following general formulae, in case of using twokinds of diamine compounds, consisting of diaminopolysiloxane and3,5-diaminobenzoic acid as carboxyl group-containing diamine:

where Ar is5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-carboxylic acidresidue. Its weight-average molecular weights Mw (determined by GPC interms of polystyrene) are about 10,000 to about 50,000, preferably about15,000 to about 30,000.

Furthermore, in case of using three kinds of diamine compoundsconsisting of diaminopolysiloxane, 4,4 ′-diamine-4″hydroxytriphenylmethane and 4,4′-bis(aminophenyl)ether, it can bepresumed that a block copolymer having further repetition units (c)represented by the following general formula in addition to therepetition units (a) and (b) represented by the foregoing generalformulae:

where Ar is5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-carboxylic acidresidue. Its weight-average molecular weights Mw are about 10,000 toabout 100,000, preferably about 20,000 to about 50,000, which is higherthan that in case of using the two kinds of diamine compounds.

The thus obtained copolymer is soluble in low boiling organic solventssuch as acetone, methyl ethyl ketone, methyl isobutyl ketone,tetrahydrofuran, ethyleneglycol monomethyl ether, chloroform, etc. oraprotic polar solvents such as dimethylformamide, dimethylacetamide,N-methyl-2-pyrrolidone, etc., and thus can be used as an organic solventsolution having a concentration of about 20-about 50 wt. %, preferablyabout 30-about 45 wt. %. The solution is admixed with a photocrosslinking agent and a photo acid-generating agent, and then dropwiseprovided onto an alkali-resistant substrate such as a quartz glasssubstrate, a copper substrate, etc. and subjected to spin coating (about500-about 2,500 rpm, preferably about 500-about 1,000 rpm, for about 10seconds) to form a film having a thickness of about 25 to about 50 μm,followed by prebaking at a temperature of about 70°-about 100° C.,preferably about 80°-about 90° C. for about 5-about 10 minutes, therebyremoving the solvent.

The thus obtained photosensitive polyimide-coated substrate is coveredwith a desired mask thereon and subjected to ultraviolet ray exposure ata dose of about 150-about 600 mJ/cm², preferably about 200-about 450mJ/cm² and then to postexposure baldng at a temperature of about110°-about 140° C., preferably about 120° about 135° C. for about5-about 10 minutes, followed by development with an aqueous solution ofan alkaline compound such as potassium hydroxide, sodium carbonate,tetramethylammonium hydroxide, etc., at a temperature of about 30°-about 50° C., thereby giving a clear negative type pattern. Thedeveloping solution herein used has a concentration of about 0.5-about4% by weight, preferably about 0.5-about 3% by weight, and thedeveloping time is preferably within about one minute. After thedevelopment, water washing, drying and curing at about 160° C. for about2 hours are carried out.

Preferable photo crosslinking agent for use in the present inventionincludes, hydroxymethyl group-containing substituted phenols such as2-hydroxymethyl-4,6-dimethylphenol, 1,3,5-trihydroxymethylbenzene,3,5-dihydroxymethyl-4-methoxytoluene[2,6-bis(hydroxymethyl)-p-cresol],etc. The photo crosslinking agent can be used in a proportion of about 1to about 50 parts by weight, preferably about 3 to about 15 parts byweight, per 100 parts by weight of polyimide. Below about 1 parts byweight, the cross-linking density is so low that no satisfactory polymermatrix is formed and thus the film will be dissolved in the aqueousalkali solution, whereas above 50 parts by weight the solubility of thecomposition is lowered, so that a crystalline pattern will be formed onthe coated surface.

Photo acid-generating agent such as nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate,diphenyliodonium-9,8-demethoxyanthracene sulfonate, etc. can be used ina proportion of about 1 to about 50 parts by weight, preferably about 3to about 20 parts by weight, per 100 parts by weight of polyimide. Belowabout 1 parts by weight, FPC pattern will be partially dissolved in theaqueous alkali solution and will be narrowed, whereas above about 50parts by weight a crystalline pattern will appear on the coated surfaceas in the case of the photo crosslinking agent.

The present invention provides a polyimide soluble in low boilingorganic solvent for general purpose use. A photosensitive compositioncontaining the present polyimide, a photo crosslinking agent and a photoacid-generating agent is developable in an aqueous alkali solution toform a negative type polyimide pattern with a distinguishedpatternability. When an aromatic or alicyclic diamine is simultaneouslyused as a diamine compound, a satisfactory photosensitivity even to athicker film can be given. Particularly in case of using an alicyclicamine, a satisfactory photosensitivity even to a film as thick as 70 μmcan be given.

PREFERRED EMBODIMENTS OF THE INVENTION

The present invention will be described in detail below, referring toExamples and Comparative Examples.

EXAMPLE 1

18.24 g (0.12 moles) of 3,5-diaminobenzoic acid and 158.4 g (0.18 moles)of diaminopolysiloxane (BY16-853U, product of Dow-Corning Co., USA;amine equivalent: 440) were charged into a separable flask having acapacity of 1 L and 79.2 g (0.3 moles) of5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-carboxylic acidanhydride as a solution in 385 g of N-methyl-2-pyrrolidone was dropwiseadded thereto, keeping at a temperature of about 0°-about 10° C. by icecooling. After the dropwise addition, the solution was heated to 50° C.and stirred at that temperature for 4 hours, and then heated to 200° C.and subjected to dehydration reaction at that temperature for 4 hours.After the reaction, the reaction mixture was put into water and theproduct was reprecipitated to obtain carboxyl group-containing polyimide(carboxyl group content: 0.80% by mole).

100 parts by weight of the resulting carboxyl group-containing polyimidewas admixed with 12.5 parts by weight of 2,6-bis(hydroxymethyl)-p-cresolas a photo crosslinking agent and 12.5 parts by weight ofdiphenyliodonium-9,10-methoxyanthracene-2-sulfonate as a photoacid-generating agent, and prepared into a solution having a solidconcentration of 40 wt. % in a solvent mixture of methyl ethyl ketoneand ethyleneglycol monomethyl ether in a ratio of 1:1 by volume.

The thus prepared photosensitive polyimide solution was spin coated ontothe lustrous surface of a copper foil at 600 rpm for 10 seconds,prebaked at 90° C. for 10 minutes to make once it into a film statehaving a thickness of 50 μm, covered with a mask (Photonix RP-1, productof Hitachi Chemical Co., Japan) thereon and exposed to ultraviolet raysat 300 mJ/cm². Then, after postexposure baking at 130° C. for 5 minutes,the mask-covered polyimide film was developed with an aqueous 3 wt. %sodium carbonate solution at 40° C. for 60 seconds, and then washed withwater at room temperature for one minute to obtain a negative typepolyimide pattern having a film thickness of 52 μm (measured by filmthickness meter).

Electron microscope observation of the resulting negative type polyimidepattern revealed that the pattern and line width were each 100 μm at100/100 (μm), showing a distinguished patternability without anyswelling.

Furthermore, a polyimide film obtained by coating onto apolytetrafluoroethylene sheet, followed by light exposure was cured at160° C. for two hours, and then subjected to a heat resistance test(180° C. for 1,000 hours), a high temperature-high humidity test (85° C.and 85%RH for 1,000 hours), or a low temperature resistance test (−50°C. for 1,000 hours). Bonding strength after respective tests wasdetermined by a cross cut method and 100/100 resulted in all the tests.

EXAMPLE 2

In Example 1, when a copper foil was coated with the photosensitivepolyimide solution, a negative type polyimide pattern having a filmthickness of 51 μm was obtained. All the three kinds of tests ofpolyimide film cured at 160° C. for 2 hours showed a bonding strength of100/100, respectively. The carboxyl group-containing polyimide had acarboxyl group content of 0.80% by mole.

EXAMPLE 3

In Example 1, the amount of 3,5-diaminobenzoic acid was changed to 20.52g (0.135 moles), and the amount of diaminopolysiloxane to 145.2 g (0.165moles), whereby a negative type polyimide pattern having a filmthickness of 50 μm was obtained. All the three kinds of tests ofpolyimide film cured at 160° C. for 2 hours showed a bonding strength of100/100, respectively. The carboxyl group-containing polyimide had acarboxyl group content of 0.98% by mole.

EXAMPLE 4

In Example 3, a copper foil was coated with the photosensitive polyimidesolution, whereby a negative type polyimide pattern having a filmthickness of 52 μm was obtained. All the three kinds of tests ofpolyimide film cured at 160° C. for two hours showed a bonding strengthof 100/100, respectively. The carboxyl group-containing polyimide had acarboxyl group content of 0.98% by mole.

EXAMPLE 5

In Example 1, 22.16 g (0.12 moles) of 2,2′-bis(aminobenzoic) acid wasused in place of 3,5-diaminobenzoic acid. Stirring time before thedehydration reaction was changed to 3 hours, light exposure dose to 450mJ/cm², and concentration of developing solution to 1% by weight. Theresulting negative type polyimide pattern showed a good patternabilityas in Example 1. The carboxyl group-containing polyimide had a carboxylgroup content of 1.5% by mole.

EXAMPLE 6

In Example 5, the amount of 3,5-diaminobenzoic acid was changed to 42.9g (0.15 moles), and the amount of diaminopolysiloxane to 132 g (0.15moles). The resulting negative type polyimide pattern showed a goodpatternability as in Example 1. The carboxyl group-containing polyimidehad a carboxyl group content of 1.1% by mole.

EXAMPLE 7

In Example 5, the amount of 2,2-bis(aminobenzoic acid) was changed to40.2 g (0.15 moles) and the amount of diaminopolysiloxane to 132 g (0.15moles). The resulting negative type polyimide pattern showed a goodpatternability as in Example 1. The carboxyl group-containing polyimidehad a carboxyl group content of 2.1% by mole.

The carboxyl group-containing polyimides obtained in the foregoingExamples 1 to 7 had weight-average molecular weights Mw of about 12,000to about 16,000.

COMPARATIVE EXAMPLE 1

In Examples 1 to 7, when no carboxyl group-containing diamine compoundwas used, all the resulting polyimides showed a remarkable lighttransmittance in the ultraviolet region, but had no carboxyl groupsoluble in an aqueous alkali solution and thus could not be developedwith an aqueous alkali solution.

COMPARATIVE EXAMPLE 2

In Example 1, the amount of 3,5-diaminobenzoic acid was changed to 13.52g (0.09 moles) and the amount of diaminopolysiloxane to 184.8 g (0.21mole). The resulting carboxyl group-containing polyimide had a carboxylgroup content of 0.55% by mole and solubility of light-unexposed regionsin an aqueous 3 wt. % Na₂CO₃ solution was not satisfactory.

COMPARATIVE EXAMPLE 3

In Example 1, when a photosensitive composition was prepared without thephoto acid-generating agent, the resulting polyimide film was notphotosensitive even if the dose was increased from 300 mJ/cm² to 1,000mJ/cm² and was dissolved even in an aqueous 1 wt. % Na₂CO₃ solution.

COMPARATIVE EXAMPLE 4

In Example 1, when a photosensitive composition was prepared without thephoto crosslinking agent, the resulting polyimide film was notphotosensitive, even if the dose was increased from 300 mJ/cm² to 1,000mJ/cm², and was dissolved even in an aqueous 1 wt. % Na₂CO₃ solution.

COMPARATIVE EXAMPLE 5

In Example 1, when 96.6 g (0.3 moles) of benzophenone tetracarboxylicacid dianhydride was used as a tetracarboxylic acid dianhydride, theresulting carboxyl group-containing polyimide (carboxyl group content:0.77% by mole) showed no substantial light transmission in theultraviolet region, particularly at wave lengths of 350 to 450 nm.

COMPARATIVE EXAMPLE 6

In Example 1, when oxydiphthalic acid dianhydride was used as atetracarboxylic acid dianhydride, the resulting carboxylgroup-containing polyimide (carboxyl group content: 0.78% by mole)showed a light transmittance of not more than 0.4 in the ultravioletregion, which was inferior to that of Example 1. Furthermore, solubilityof the photosensitive composition in the solvent mixture was only 20% byweight.

EXAMPLE 8

13.68 g (0.09 moles) of 3,5-diaminobenzoic acid, 18.0 g (0.09 moles) of4,4′-bis(aminophenyl) ether and 105.6 g (0.12 moles) ofdiaminopolysiloxane (BY16-853U) were charged into a separable flaskhaving a capacity of 1 L and 79.2 g (0.3 moles) of5-(2,5-dioxotetrahydrofuryl)-3-cydohexene-1,2-carboxylic acid anhydridewas added thereto as powders, keeping at a temperature of about 0°-about10° C. by ice cooling. Then, 300 g of N-methyl-2-pyrrolidone was addedthereto to dissolve the acid anhydride. After the dissolution, thesolution was heated to 50° C. and stirred at that temperature for 3hours, and then heated to 200° C. and subjected to dehydration reactionat that temperature for 3 hours. After the reaction, the reactionmixture was put into water and the product was reprecipitated to obtaincarboxyl group-containing polyimide (carboxyl group content: 0.76% bymole).

100 parts by weight of the resulting carboxyl group-containing polyimidewas admixed with 12.5 parts by weight of 2,6-bis(hydroxymethyl)-p-cresoland 12.5 parts by weight ofdiphenyliodonium-9,10-methoxyanthracene-2-sulfonate, and prepared into asolution having a solid content concentration of 40% by weight in asolvent mixture of methyl ethyl ketone and ethyleneglycol monomethylether in a ratio of 3:7 by volume.

The thus prepared plustosensitive polyimide solution was spin coatedonto the lustrous surface of a copper foil at 500 rpm for 10 seconds;prebaked at 90° C. for 10 minutes to make once it into a film statehaving a thickness of 50 μm, covered with a mask (Photonix PR-1) thereonand exposed to ultraviolet ray at 300 mJ/cm². Then, after postexposurebaking at 120° C. for 5 minutes, the mask-covered polyimide film wasdeveloped with an aqueous 3 wt. % sodium carbonate solution at 40° C.for 60 seconds, and then washed with water at room temperature for oneminute to obtain a negative type polyimide pattern.

Electron microscope observation of the resulting negative type polyimidepattern revealed that the pattern and line width were each 100 μm at100/100 (μm), showing a good patternability without any swelling.

EXAMPLE 9

In Example 8, 40.7 g (0.09 moles) of4,4′-[bis(3-aminophenoxy)phenyl]-sulfone was used in place of4,4′-bis(aminophenyl)ether. The resulting negative type polyimidepattern showed a good patternability as in Example 8. Carboxyl groupcontent of the carboxyl group-containing polyimide was 0.77% by mole.

EXAMPLE 10

In Example 8, 26.3 g (0.09 moles) of 1,3-bis(4-aminophenoxy)benzene wasused in place of 4,4′-bis(aminophenyl)ether. The resulting negative typepolyimide pattern had a good patternability as in Example 8. Carboxylcontent of the carboxyl group-containing polyimide was 0.71% by mole.

EXAMPLE 11

In Example 8, 12.8 g (0.09 moles) of 1,3-bis(aminomethyl)cyclohexane wasused in place of 4,4′-bis(aminophenyl) ether. The resulting negativetype polyimide pattern had a good patternability as in Example 8.Carboxyl content of the carboxyl group-containing polyimide was 0.80% bymole.

Carboxyl group-containing polyimides obtained in the foregoing Examples8 to 11 had weight average molecular weights Mw of about 30,000 to about50,000.

What is claimed is:
 1. A photosensitive composition, which comprises apolyimide comprising a copolymer of two kinds of diamine compoundsconsisting of diaminopolysiloxane and a carboxyl group-containingdiamine or three kinds of diamine compounds consisting ofdiaminopolysiloxane, a carboxyl group-containing diamine and an aromaticor alicyclic diamine, and a dicarboxylic acid anhydride having a2,5-dioxotetrahydrofuryl group as one acid anhydride group, and a photocrosslinking agent and a photo acid-generating agent.
 2. Aphotosensitive composition according to claim 1, wherein the polyimidecopolymer has a carboxyl group content of 0.6 to 3% by mole.
 3. Anegative type polyimide pattern obtained by subjecting thephotosensitive composition according to claim 1 to light exposure,followed by development with an aqueous alkali solution.